Cannabinoid was discovered as the main active substance contained in marijuana in 1960 and found to exhibit an activity to the central nervous system (illusion, euphoria, sensory confusion of time and space) and an activity to the peripheral cell system (immunosuppressive activity, anti-inflammatory activity, analgesic activity).
After that, anandamide and 2-arachidonoylglycerol produced from phospholipid containing arachidonic acid were discovered as endogenous agonists to a cannabinoid receptor. These endogenous agonists were known to exhibit an activity to the central nervous system and an activity to the peripheral cell system. It was disclosed in Hypertension (1997) 29, 1204–1210 that anandamide exhibits an activity to the cardiovascular system.
A cannabinoid type 1 receptor discovered in 1990 was found to distribute in the central nervous system such as the brain. Agonists to this receptor were found to suppress the release of neurotransmitters to cause central actions such as illusion or the like. A cannabinoid type 2 receptor discovered in 1993 was found to distribute in immune tissues such as the spleen or the like. Agonists to this receptor were found to suppress an activation of cells in immunocyte or phlogocyte to exhibit an immunosuppressive activity, an anti-inflammatory activity and an analgesic activity (Nature, 1993, 365, 61–65).
Therefore, selective antagonists or agonists to the cannabinoid type 2 receptor are expected as immunosuppressive agents, anti-inflammatory agents, analgesic agents without causing side effects on the central nervous system such as illusion or the drug dependence, which are associated with the cannabinoid type 1 receptor (Nature, 1998, 349, 277–281).
Known as compounds having an antagonistic activity or agonistic activity to the cannabinoid type 2 receptor are isoindolynone derivatives (WO97/29079 and WO99/02499), pyrazole derivatives (WO98/41519) and the like.
On the other hand, Japanese Patent Publications (Kokai 1986-65894, Kokai 1987-29594) disclose that organophosphorus compounds having a 2-imino-1,3-thiazine skelton are useful as insecticides.
However, it is not known that 2-imino-1,3-thiazine derivatives have an antagonistic activity or agonistic activity to the cannabinoid type 2 receptor.